Filter device having a pump

ABSTRACT

The invention relates to a filter device, in particular provided for use with diesel fuels, comprising a filter element (19) that can be exchangeably accommodated in a filter housing, which filter device is characterized in that a fluid pump device (46) having two pump chambers (45, 49) is present as part of the filter device, which pump chambers, by means of a pump piston (51) guided in said chambers in a longitudinally movable manner, are separated from each other in a fluid-tight manner at least in one of the two directions of movement of the pump piston, and that each pump chamber (45, 49) is assigned a valve (39, 63), which opens or closes oppositely to the other valve (39, 63) when the pump device (46) is actuated.

The invention relates to a filter device, in particular provided for use with diesel fuels, comprising a filter element that can be exchangeably accommodated in a filter housing. Further, the invention relates to a supply system for an internal combustion engine.

In systems for supplying consumers or recipients with fluids, such as liquid fuels for the operation of internal combustion engines, it is state of the art (DE 10 2009 008 676 A1) to connect filter devices upstream of the associated feed pumps, in order to withhold pollutants endangering the operational reliability. For supply systems for diesel engines, ordinarily a filter device is connected upstream of a pre-feed pump in the intake line for diesel fuel, which as a pre-filter removes the main pollution load including water from the fuel supplied to the tank, before the pre-feed pump continues supplying the fuel via a fine mesh filter to the injection pump, which is part of the injector system, for example in the form of a common rail system. In the operation of these systems the filter element of the filter device which, as a pre-filter cleans the brunt of the pollutants, is to be replaced after the appropriate operating time. For these operations taking place with an at least partially emptied filter housing, air is introduced into the system, which must be removed in order to ensure the delivery operation of the pre-feed pump. To this end, in the state of the art hand pumps are used, with which the air can be extracted and which can be connected in conjunction with associated valve devices from the outside on the relevant filter housing. The maintenance work that must be carried out for a filter element replacement is therefore laborious and time-consuming.

With regard to this problem, the invention addresses the problem of providing a filter of the type in question, which is characterized by a particular ease of maintenance.

In accordance with the invention, this problem is solved by a filter device which has the features of claim 1 in its entirety.

According to the characterizing part of claim 1, the invention is characterized by the fact that the filter device has a fluid pump device with two pump chambers as part of the filter device, which by means of a pump piston guided longitudinally movably in these chambers are separated from one another in a fluid tight manner at least in one of its two directions of travel, wherein provision is made that each pump chamber is assigned a valve, said valve working in opposite direction to the respective other valve upon actuation of the pump device opens or closes. Hence, the entire device required for extracting the introduced air, including the pump devices and the assigned valves, is integrated in the inventive filter device. Due to the fact that no external devices have to be used and no work is required for the connection of the devices, the maintenance work associated with a replacement of the filter element can be carried out quickly and safely and thus cost-effectively.

The pump device is a permanent part of the filter device, wherein a part is arranged in the filter housing with the filter element to be replaced, and in particular the pump piston to be operated preferably by hand, which divides the two pump chambers, is arranged on the cover side or the head side of the filter housing.

For particularly advantageous embodiments, at least the one valve is part of the filter element and in its opened position transfers fluid to its assigned pump chamber, while it blocks this route in its closed position. In a filter element replacement with an associated entry of air into the filter housing, it is in the process transferred to the pump chamber via this opened valve during activity of the pump device.

With particular advantage, the other, second valve can be part of the filter housing, in particular of its housing head, which can be bolted back onto a housing pot in detachable manner with the accommodating filter element, wherein in its opened position this valve transfers fluid to its assigned pump chamber and in its closed position it blocks this route. On the other hand, as was the case with the first valve, during the activity of the pump device, air that is introduced into the housing in the event of a filter element replacement is transferred together with the fuel present in the housing to the assigned pump chamber. Alternatively, both valves can also be part of the filter element or of the filter housing.

With particular advantage, the arrangement can be made such that the pump piston is connected to a rod-shaped actuation device, which, led out of the filter housing, by means of a handle enables the movement of the pump piston by hand in its two pump chambers. As a result, the extraction of air from the filter housing is especially easy and convenient. The pump chamber of the filter element that can be connected to the clean side of the filter by means of the first valve can have a fluid connection for further transport of the fluid to a pre-feed pump, preferably a diesel injection system. As a result, the pump device forms a feed device connected further upstream of the pre-feed pump, which through its operation extracts air out of the filter housing and after its removal, feeds suctioned fuel to the pre-feed pump and in the course of pump actuation fills it with fuel, so that a secure start of the pre-feed pump and thus the secure restart of the total supply system is ensured.

In the process, the arrangement can be advantageously made such that, in passing through the pump chamber which receives the fluid from the second valve in its open position, in the direction of its decreasing chamber volume, fluid from this chamber is displaced via the pump piston in the direction of the other pump chamber. As a result, the pump chamber, from which, during a forward stroke the fluid is displaced to the pre-feed pump, can be refilled during a return stroke of the pump piston for the next forward or delivery stroke.

For this filling function the pump piston can have an elastically flexible edge along its outer periphery, which in the one direction of travel of the pump piston permits fluid flow from the one pump chamber to the other and in the other direction of travel, thus during a delivery or forward stroke, blocks this route.

In advantageous exemplary embodiments the valve of the filter element has a valve ball, which, guided in a cage with fluid passages, is part of an end cap of the filter element, which faces the assignable pump chamber.

In such a way this valve can be realized as a check valve in a simple design.

Advantageously, the other valve can be formed from a spring loaded check valve, whose intake duct is connected to the clean side of the filter element. The spring loading is, in this connection, set such that this valve opens automatically for inflowing fluid when the pump piston moves in the direction increasing the volume of the connected pump chamber.

According to claim 10, the subject matter of the invention is also a supply system for an internal combustion engine, having a filter device according to any of claims 1 through 9. Such a supply system can be used with particular advantage for the supply of diesel engines and in particular is also suitable for large stationary diesel engines.

In the following the invention will be explained in greater detail on the basis of an exemplary embodiment shown in the drawing.

The figures show the following:

FIG. 1 shows a flow chart of the fluid circuit of a fuel supply system according to the prior art;

FIG. 2 shows a top view partially horizontally sectioned and drawn in broken lines top view of the exemplary embodiment of the inventive filter device;

FIG. 3 shows a longitudinal section of the housing head of the filter housing of the exemplary embodiment in larger scale and drawn in broken lines;

FIG. 4 shows a perspective diagonal view of the housing head of the filter housing of the exemplary embodiment in broken lines and drawn partially in vertical section and in horizontal section with a drawn back pump piston of the pump device;

FIG. 5 shows a perspective diagonal view of the housing head in broken lines and drawn in vertical angular section with a retracted pump piston of the pump device; and

FIG. 6 shows a longitudinal section of the separately displayed filter element of the exemplary embodiment.

FIG. 1 shows a conventional supply system for supplying fuel to an internal combustion engine, wherein a pre-feed pump 1 extracts fuel from a fuel tank 3 via an intake line 5, in which a pre-filter 7 connected upstream of the pre-feed pump 1 is arranged. From the pre-feed pump 1 the fuel goes to a fine mesh filter 9, which is connected upstream of a fuel pump 11, which supplies an injector system 13, for a diesel engine, for example, in the form of a common rail system.

In such systems, at least for the pre-filter 7, a filter element replacement must be performed after the expiration of the appropriate operating time, which can result in the entry of a considerable quantity of air into the system. Therefore, to continue operation after the filter replacement ventilation measures are required, in order to remove the incoming air, which 2 0 would impede or prevent the feed function of the pre-feed pump, from the system for the continued operation of the system. As already mentioned, to this end ordinarily extraction devices are connected on the pre-filter 7 (not shown in the figure) and put into operation.

In the case of the inventive device, of which an exemplary embodiment is presented in FIGS. 2 through 6, an extraction device is integrated in the housing head 15, which, as a fluid-tight seal can be screwed onto a filter pot not shown in the figures. Said filter pot is configured in the usual design for such filter devices and accommodates a filter element 19, which is shown separately in FIG. 6 and can be removed for replacement after unscrewing the housing head 15 from the housing pot 16. The filter element 19 has, in the usual manner, a filter medium 25 between the upper end cap 21 and the lower end cap 23, in the exemplary embodiment in the form of a mesh pack forming a hollow cylinder, which serves as a coalescer device, said coalescer device promoting the formation of drops in the water contents in the diesel oil, said drops descending in the inner cavity 29 and forming a sump on the open lower end cap 23, which can be conveyed from there to the outside. A fluid-permeable support tube 27, which is in contact with the inside of the filter medium 25, surrounds the inner filter cavity 29, which forms the clean side in operation during the through flow occurring from the outside of the filter medium 25 to the inside. In the central opening 31 of the upper end cap 21 a hollow retaining body 33 is located for a water repellent (hydrophobic) barrier layer 35 (FIG. 6). In particular, a descent occurs from the element 19 to the water accumulator of the housing pot 16.

The hollow retaining body 33 fixed on the upper end cap 21, which forms an outlet from the inner cavity 29 forming the clean side, has a collar of fingers 37 protruding upward, which form a kind of cage for a valve ball 39. In addition, a valve seat 41 is formed for the valve ball 39 in the passage of the retaining body. At the transition to the retaining fingers 37, at about the height of the valve seat 41, an O-ring 42 is located at the outside of the retaining body 33. At a radial distance to this on the upper end cap 21 there is an annular, upward protruding extension 43, in which a further O-ring 44 is accommodated.

FIGS. 2, 4 and 5 show the check valve formed by the valve ball 39 and the valve seat 41, designated as the first valve here, in each case in the closed position, in which case the fluid connection between the inner filter cavity 29 on the clean side and an inlet 44 is blocked at a first pump chamber 45 of a pump device 46. Said pump device has an inlet 48 to a second pump chamber 49 on its pump cylinder 47. The pump cylinder 47 with pump piston 51 traveling between the pump chambers 45 and 49 is arranged above the filter element 19 with a horizontal cylinder axis in the housing head 15.

The housing head 15 has two hollow cylinders coaxial to the longitudinal axis of the filter element 19 and concentric to one another which are open on the side facing the end cap 21 of the filter element 19 as a holding fixture for the filter element 19 and for the formation of fluid connections. The inner hollow cylinder is numbered 53 and the outer hollow cylinder surrounding it at a radial distance is numbered 55. If the filter element 19 is inserted in its functional position, the O-ring 42 forms the seal of a fluid connection between the retaining body 33 and the inside wall of the inner hollow cylinder 53, which for an opened valve, i.e., for a valve ball 39 raised from the valve seat 41, as shown in FIG. 3, leads from the inside of the sieve pipe 35 to the inlet 44 of the first pump chamber 45. The radial O-ring 44 lying further outward forms the seal between the extension 43 of the end cap 21 and the inside of the outer 30 hollow cylinder 55. As a result, a second sealed fluid connection is formed between the annular space 57 between the inner hollow cylinder and the outer hollow cylinder via an outlet 59 of the end cap 21 to the clean side space 61 between the support tube 27 and the sieve pipe 35. FIGS. 2 and 3 show that in the housing head 15 a second valve 63 is arranged above the pump cylinder 47 such that its inlet 65 overlaps the upper end 67 of the clean side annular space 57, so that, see FIG. 2, a fluid connection is formed from the clean side to the inlet 65 of the second valve 63.

The pump piston 51 can be operated manually by means of a handle 71 mounted on its piston rod 69 in the pump cylinder 47 between the first pump chamber 45 and the second pump chamber 49. The pump piston 51 has an elastically flexible edge 72 on the piston circumference, which in the manner of a membrane in moving into the position shown in FIGS. 2, 3 and 5, when the volume of the first pump chamber 45 is reduced and the volume of the second pump chamber 49 is increased, forms a fluid-tight seal on the inside wall of the pump cylinder 47, however, when retracted to the position shown in FIG. 4 permits the overflowing of the pump piston 51, so that fluid present in the second pump chamber 49, reaches the first pump chamber 45 when its volume is reduced. The second valve 63 is a check valve with valve bodies 75 loaded by a compression spring 73, which opens for the passage of fluid from the inlet 65 to the second pump chamber 49 via its inlet 48 when actuated by pressure.

For the operation of the pump device 46 during the retraction of the pump piston 51 from the position shown in FIGS. 2, 3 and 5 to the position shown in FIG. 4, wherein the volume of the first pump chamber 45 is increased, the first valve opens by raising the valve ball 39, see FIG. 3, where the start of the return travel is shown. In the process, fluid, i.e., air and remaining fuel, flows from the filter element 19 via the inlet 44. Simultaneously, fluid present in the second pump chamber 49 due to the overflow of the pump piston 51 reaches the first pump chamber 45, because during the return travel the second valve 63 is closed. During a subsequent insertion of the piston 51 from the position shown in FIG. 4, the valve ball 39 of the first valve closes and the total fluid collected in the first pump chamber 45 is conducted via an outlet 77 to the pre-feed pump 1. Simultaneously, during this piston motion the second valve 63 opens, so that fluid flows via its inlet 65 over the space 57 from the clean side. During repeated operating cycles with further actuation of the pump device 46 air will be removed from the filter housing and, if necessary, any present inflowing fuel will be transported to the downstream pre-feed pump 1, ensuring a secure function after replacement of a filter element. 

1. A filter device, in particular provided for use with diesel fuels, comprising a filter element that can be exchangeably accommodated in a filter housing (19), characterized in that a fluid pump device (46) with two pump chambers (45, 49) is present, which by means of a pump piston guided longitudinally movably in these chambers (51) at least in one of its two directions of travel are separated from one another in a fluid tight manner and wherein for each pump chamber (45, 49) assigned a valve (39, 63) provision is made that working in opposite direction to the respective other valve (39, 63) upon actuation of the pump device (46) opens or closes.
 2. The filter device according to claim 1, characterized in that at least the one valve (39) is part of the filter element (19) and in its opened position transfers fluid to its assigned pump chamber (45) and in its closed position blocks this route.
 3. The filter device according to claim 1, characterized in that the other valve (63) is part of the filter housing, in particular of a housing head (15), which can be screwed back onto a housing pot (16) in detachable manner with the accommodating filter element (19), and that the other valve (63) in its opened position transfers fluid to its assigned pump chamber (49) and in its closed position blocks this route or that both valves (39, 63) are part of the filter element (19).
 4. The filter device according to claim 1, characterized in that the pump piston (51) is connected to a rod-shaped actuation device (69), which, led out of the filter housing, by means of a handle (71) enables the movement of the pump piston (51) in its two pump chambers (45, 49) by hand.
 5. The filter device according to 1, characterized in that the pump chamber (45), of the filter element (19) that can be connected to the clean side (29) of the filter element (19) by means of the one valve (39), has a fluid connection (77) for the further transport of the fluid to a pre-feed pump (1), preferably a diesel injection system.
 6. The filter device according to claim 1, characterized in that in passing through the pump chamber (49) which receives the fluid from the other valve (63) in its open position, in the direction of its decreasing chamber volume, fluid from this chamber (49) is displaced via the pump piston (51) in the direction of the other pump chamber (45).
 7. The filter device according to claim 1, characterized in that the pump piston (51) has an elastically flexible edge (72) along its outer periphery, which in the one direction of travel of the pump piston (51) permits fluid flow from the one pump chamber (49) to the other (45) and in the other direction of travel blocks this route.
 8. The filter device according to claim 1, characterized in that the valve of the filter element (19) has a valve ball (39), which, guided in a cage (37) with fluid passages, is part of an end cap (21) of the filter element (19), which faces the assignable pump chamber (45).
 9. The filter device according to claim 1, characterized in that the other valve (63) is formed from a spring loaded check valve (73, 75) whose intake duct (65) is connected to the clean side (57) of the filter element (19).
 10. Supply system for an internal combustion engine with a fluid with an upstream pre-feed pump (1) and main feed pump (11), characterized in that, viewed in the fluid delivery direction, a filter device (19, 46) according to claim 1 is connected upstream of the pre-feed pump (1). 